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COSC1078 Introduction to Information Technology Lecture 4 Images PowerPoint PPT Presentation


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James Harland [email protected] COSC1078 Introduction to Information Technology Lecture 4 Images. Introduction to IT. 1 Introduction 2 Images 3 Audio 4 Video WebLearn Test 1 5 Computer Fundamentals Assignment 1

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James harland james harland@rmit edu au

Intro to IT

James Harland

[email protected]

COSC1078 Introduction to Information TechnologyLecture 4Images


Introduction to it

Intro to IT

Introduction to IT

1 Introduction

2 Images

3Audio

4Video WebLearn Test 1

5 Computer Fundamentals Assignment 1

6 Computer Fundamentals

7Computer Fundamentals

8 Operating Systems WebLearn Test 1

9 Operating Systems Assignment 2

10 Internet

11Internet Security WebLearn Test 3

12Future of ITAssignment 3, Peer and Self Assessment


Overview

Intro to IT

Overview

  • Questions?

  • Images

  • Assignment 1

  • Lab classes

  • Questions?


Introduction

Intro to IT

Introduction

James Harland

  • Email:[email protected]

  • URL:www.cs.rmit.edu.au/~jah

  • Phone:9925 2045

  • Office:14.8.13 (Building 14, level 8, room 13)

  • Consultation:Wed 1.30-2.30, Thu 11.30-12.30

    What colour is my office door? Carpet? Chair?


Representing colours

Representing Colours

01010100001010101010100110100010101001101001010010100011100010101010100101111001001010…

R

Pixel

G

B

Lecture 4: Images

Intro to IT


Representing colours1

Representing Colours

  • There are various different schemes for representing colours

  • RGB

  • CMYK

  • HSB

  • HSL

  • CIE XYZ

01010100001…

Lecture 4: Images

Intro to IT


Cosc1078 introduction to information technology lecture 4 images

RGB

  • Human eye uses red, green, blue sensors

  • Additive --- more colours means lighter colour

+

yellow

+

cyan

+

magenta

+

+

Other colours by varying amounts of R, G, B

Lecture 4: Images

Intro to IT


Cosc1078 introduction to information technology lecture 4 images

RGB

  • Often represented as (#R, #G, #B) where #R, #G, #B in range 0, 1, …, 255 (ie 28 -1)

  • This means 8 bits per channel, or bit depth 24

  • Gives 2563 = 16,777,216 colours overall

  • Note that RGB is a scheme, not a particular set of numbers

Lecture 4: Images

Intro to IT


Rgb 8 bits per channel

RGB 8 bits per channel

Lecture 4: Images

Intro to IT


Cosc1078 introduction to information technology lecture 4 images

CMYK

  • Based on 4 colours

  • Subtractive – more colours means less light

Cyan

Magenta

Yellow

blacK

+

yellow

+

cyan

+

magenta

Lecture 4: Images

Intro to IT


Cmyk why black why not cmy

CMYK Why Black? Why not CMY?

+

+

  • Used mainly in printing (“4-colour print”)

  • In practice, doesn’t look “black”

  • “There is no colour with more shades than black”

  • Too much ink to make black soaks the paper too much

  • Text is traditionally black (and lots more text than pictures in colour)

  • Black ink is cheaper than coloured

Lecture 4: Images

Intro to IT


Representing colours2

Representing Colours

  • There are various different schemes for representing colours

  • RGB

  • CMYK

  • HSB

  • HSL

  • CIE XYZ

01010100001…

Lecture 4: Images

Intro to IT


Hsb or hsv

HSB (or HSV)

How do humans describe colour?

“rich dark green”

Hue: basic colour (red, green, blue, yellow, …)

Saturation: amount of colour (intensity, purity)

Brightness: light or dark or in-between …

Can be thought of as a cone or cylinder or hexacone

Lecture 4: Images

Intro to IT


Hsb and hsv and hsl

HSB and HSV and HSL

  • Hue is represented on a circle, and hence as a bearing (like on a compass)

  • Saturation and Brightness/Value are percentages

  • HSL is similar, except that 100% luminance is always white (just as 0% brightness is black)

Lecture 4: Images

Intro to IT


Cie xyz

CIE XYZ

  • Standard derived from work in 1931 to identify all colours visible to humans

  • Colours divided into brightness and chromacity

  • Humans can see more colours than a typical monitor can display

  • RGB produces more colours than CMYK

Lecture 4: Images

Intro to IT


Assignment 1

Intro to IT

Assignment 1

  • Use GIMP (or a similar tool) to perform some manipulations on an image

  • Address two issues in relation to this

  • Lab classes 2 and 3 will be based around GIMP

  • Main emphasis is on process, not result!

  • Will be released (on the Learning Hub) by Wednesday 10th March (later today)


Lab classes

Lab Classes

Start in week 2 (this week)

Work on practical exercises and sometimes assignment materials

Lab assists present to help and an answer questions

Details will be in the Learning Hub

Lecture 4: Images

Intro to IT


Conclusion

Intro to IT

Conclusion

  • Go to laboratory classes (and tutorials) this week!

  • Lab notes in the Learning Hubub

  • Check details in Course Guide

  • Start reading (notes, problems, report topic)

GET THE BOOK!


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